Mixed reality or augmented interactive input systems are known in the art. Some existing augmented interactive input systems make use of a document camera to track physical objects such as cubes and flashcards that comprise recognizable patterns. Digital content is superimposed on top of the images captured by the document camera. The direct association of the physical objects to digital content allows users to manipulate the digital content through manipulation of the physical objects. Unfortunately, these augmented interactive input systems have only permitted the position and orientation of physical objects to be tracked. As a result, user manipulations of digital content in this scenario have been limited to translations and rotations of physical objects. By only permitting the position and orientation of the physical objects to be tracked, interactions such as clicking a button or opening a menu have been difficult to realize without use of an external input device such as a mouse or keyboard.
Another problem that occurs in existing augmented interactive input systems is the temporary loss of physical objects that are being tracked. When an augmented interactive input system loses track of a physical object and then regains tracking of the physical object, the associated digital content shown on the display disappears and then quickly re-appears, causing unwanted flickering.
Another problem with these augmented interactive input systems is that they generally employ physical markers, such as, paper-based markers, which are difficult to identify under poor ambient lighting conditions. Additionally, proper identification of the marker may be severely affected by light reflecting off of the surface of the marker, or by shadows or other occlusions of portions of the marker.
The publication entitled “Occlusion based Interaction Methods for Tangible Augmented Reality Environments,” authored by Lee et al. and published in the Proceedings of the 2004 ACM SIGGRAPH international conference on Virtual Reality continuum and its applications in industry (pages 419-426, 2004), discloses an occlusion based interaction system and method for interacting with two-dimensional (2D) digital objects in a camera-based tangible augmented reality environment. A marker comprising a set of patterns is imaged by a camera, and patterns on the marker are recognized. When a user uses a finger to manipulate the marker and the finger occludes at least one pattern on the marker, the interaction system determines which pattern has been occluded, and then performs a 2D action (e.g., clicking a button or opening a menu) accordingly. Because multiple patterns are required, either the marker has to be sufficiently large so as to accommodate the patterns, making the marker, as a physical object, difficult to manipulate, or the patterns have to be small, which may increase the failure rate of pattern recognition.
As will be appreciated, improvements in mixed reality or augmented interactive input systems are desired. It is therefore an object of the following to provide a novel interactive input system having a three-dimensional input space.